Shrinkproofing wool with oxidizing agents using foulard liquid application technique

ABSTRACT

Shrinkproofing of continuous lengths of wool is effected by wetting-out wool with an aqueous solution containing predetermined amounts of (a) a wetting agent, (b) a halogencontaining shrink-resistance-imparting oxidizing agent for wool, and (c) a source of hydrogen ion other than a per acid present in an amount sufficient to reduce the pH of the solution to below 5, immediately passing the wetted-out wool through a precision nip and then allowing the thus predetermined amount of solution to remain in contact with the wool while the desired oxidation takes place. The solution containing the acidified halogen-containing shrink-resistance-imparting oxidizing agent is an unstable one and is freshly prepared from stable solutions as it is used up. The rate of admixture of the stable solutions is correlated with the rate of pickup of liquor by the wool so that the volume of prepared treating liquor remains constant and complete renewal thereof takes place in 1 to 15 minutes.

United States Patent Continuation of application Ser. No. 463,419, May 5, 1965, now abandoned. This application Apr. 30, 1970, Ser. No. 31,832

[54] SHRINKPROOFING WOOL WITH OXIDIZING AGENTS USING FOULARD LIQUID APPLICATION TECHNIQUE 9 Claims, 1 Drawing Fig.

[52] U.S. Cl 8/l27.6, 8/128 [51] Int. Cl 006m 3/08, D06m 3/12, D06m 13/38 [50] Field of Search 8/127.6, 128; 68/22 B [56] References Cited UNITED STATES PATENTS 2,993,747 7/l96l Scott 8/l27.6 3,144,300 8/1964 Cosnard et al 8/l27.6

FOREIGN PATENTS 763,965 12/1956 Great Britain Primary Examiner-George F. Lesmes Assistant Examiner-J Cannon Attorney-Wenderoth, Lind & Ponack ABSTRACT: Shrinkproofing of continuous lengths of wool is effected by wetting-out wool with an aqueous solution containing predetermined amounts of (a) a wetting agent, (b) a halogen-containing shrink-resistance-imparting oxidizing agent for wool, and (c) a source of hydrogen ion other than a per acid present in an amount sufficient to reduce the pH of the solution to below 5, immediately passing the wetted-out wool through a precision nip and then allowing the thus predetermined amount of solution to remain in contact with the wool while the desired oxidation takes place. The solution containing the acidified halogen-containing shrink-resistanceimparting oxidizing agent is an unstable one and is freshly prepared from stable solutions as it is used up. The rate of admixture of the stable solutions is correlated with the rate of pickup of liquor by the wool so that the volume of prepared treating liquor remains constant and complete renewal thereof takes place in l to 15 minutes.

PAIENIEUnmzmn 3628.909

: c CI 1 2 SOD/UM DICHLOROCYANURAE L 40/0 WOOL C; AND C; CONSTANT HEAD TANKS F7 AND F; FLOWMETERS M MIXING TANK N R RESERVOIR N N/P CONTAINING TREA TMENT BA TH 70 BRATT/C OR SCRA Y //VVNTOk$ 00M film ATronuEYs containing wool which areavailable in continuous form or which can readily be joined together into a continuous form to enable the same to be subjected to substantially uniform treatment.

Woolen materials which are available in continuous form include yarns, tops and woven and knitted fabrics consisting of or containing wool. Lengths which serve as a continuous form may also be formed by sewing together knitted garments such as socks: these are then separated after completion of the treatment.

Processes are known for the treatment of wool to impart shrink resistance thereto which involve the application of a halogen-containing reagent to wool. The appearance of the treated goods depends upon the pH value of the solution with which they have been treated. Thus, in the case of the alkali metal dichloroisocyanurates, these normally dissolve in water to produce a solution having a pH value greater than 6. These solutions are comparatively stable but when applied to wool to impart shrink resistance thereto they simultaneously produce an undesirable strong yellow coloration. If, however, a source of hydrogen ion is present in the solution in an amount sufficient to reduce the pH value of the solution, e.g. to 2.0 to 4.0, no yellowing occurs. However, at these pH values the dichloroisocyanurate solutions precipitate and lose chlorine on standing. It thus becomes both dangerous and difficult to use large static baths of these reagents at pH values which avoid yellowing.

Similar difficulties have been encountered with the alkali metal hypochlorites which can likewise be used in aqueous solution to impart shrink resistance to wool.

It is accordingly an object of the present invention to provide an improved continuous process for imparting shrink resistance to wool in a continuous form in which the wool is treated with a halogen-containing shrink-resistance-imparting reagent under conditions which avoid substantial yellowing of the treated material.

According to the present invention there is provided a process for imparting shrink resistance to wool and wool-containing materials which comprises wetting-out a continuous form of such a material with an aqueous liquor containing (a) a wetting agent, (b) a halogen-containing shrink-resistanceimparting oxidizing agent for wool and (c) a source of hydrogen ion other than a per acid present in an amount sufficient to reduce the pH value of the solution to below 5, the anion of said source of hydrogen ion being inert with respect to said halogen-containing oxidizing agent, and substantially immediately after wetting-out, passing the wetted-out material through the nip between a pair of rollers so as to ensure that the material is unifonnly impregnated with a controlled amount of said liquor and maintaining said controlled amount of liquor in contact with said material until at least a desired amount of said halogen-containing oxidizing agent has reacted with the wool with which it is in contact. Preferably the pH value of the solution is reduced to between 2.5 and 4.5.

According to a feature of the invention metered quantities of aqueous solutions of said halogen-containing oxidizing agent and of said source of hydrogen ion are fed into said aqueous liquor to maintain a substantially constant composition, which quantities are correlated with the rate of pickup of liquor by the woolen materials undergoing treatment so that (a) the volume of liquor remains substantially constant and (b) complete renewal of liquor takes place in l to minutes.

While the invention may be performed in various manners and employing various halogen-containing reagents, it is of especial application to the treatment of wool with sodium and potassium dichloroisocyanurates in aqueous baths at pH values below 5.0. The nature of the changes which occur when an aqueous solution of these salts is treated with a source of hydrogen ion is not yet fully understood, but it is believed to involve inter alia replacement of alkali metal ion by hydrogen ion in the dichloroisocyanurate molecule and subsequent isomerization of the latter. It is assumed that available chlorine is derived from an isomerized form of dichloroisocyanuric acid.

The source of hydrogen ion may be a mineral acid such as hydrochloric acid or sulfuric acid, a strong organic acid such as trichloroacetic acid or an acid salt of a strong polybasic acid such as sodium or potassium hydrogen sulfate.

The source of hydrogen ion should, however, be free from peroxy groups since such compounds per se are oxidizing agents which react with wool and their use gives rise to a special problem. Thus, the use, for example, of perrnonosulfuric acid or peracetic acid is outside the scope of the present process.

In carrying out the process of the present invention it is convenient to employ two reservoirs respectively containing an aqueous solution of the halogen-containing substance and an aqueous solution of the source of hydrogen ion. Either or both of these solutions may contain a wetting agent. While any kind of wetting agent may be employed an anionic or a nonionic wetting agent is preferred. These two solutions in metered quantities are admixed only shortly prior to application to the woolen material undergoing treatment. The concentrations of the two solutions and the proportions in which they are admixed should be such as to secure a pH value in the admixture below 5, preferably between 2.5 and 4.5 and most preferably between 2.5 and 3.5. Since the resulting solution is unstable, this admixture should only take place shortly before the resulting liquor is to be used. Lower pH values such as 0.5 or L0 are permissible but are not necessary.

In one form of the invention the woolen material is supplied with a controlled amount of treating liquor by passage through a bath of small capacity which receives liquor from the reservoirs referred to above. The liquids from the two reservoirs may, and preferably are, mixed on their way to the treating bath. The wetted-out material is then substantially immediately passed between the nip of a pair of precision rollers adjoining the exit from the bath. The nip at these rollers is so adjusted as to ensure that the woolen material passing therethrough retains within its interstices a volume of treating liquor containing an amount of the halogen-containing shrinkresistance-imparting substance sufficient to impart to the material a predetermined shrink resistance within a given time. After passing through the precision nip the liquor-containing goods are run forward over and under rollers or on a brattice or scray or otherwise retained in contact with the liquor for a time sufiicient to allow the whole of the halogencontaining substance, or any predetennined proportion thereof which will suffice to impart the desired shrink re sistance effect, to react with the woolen fibers. The pickup of aqueous liquor at the nip may be 50-250 percent, preferably -150 percent, of the weight of the woolen material.

It should be noted that the time of residence or immersion in the bath is substantially only sufficient to ensure that the goods are fully wetted out by the aqueous liquor in the bath. A preferred time of residence or immersion of the wool in the bath is l to 2 seconds. This is sufficient time to ensure thorough penetration and wetting out but insufficient time to allow any significant exhaustion of the bath liquor. The concentration of the liquor in the treatment bath remains virtually identical with that of the liquor fed into the bath throughout the process. A bath having a capacity of l to 2 gallons of liquor is contemplated although smaller and somewhat larger baths may be used if the circumstances, such as the rate of removal of liquor from the bath, require. it is a feature of the invention that the volume of liquid admitted to the bath is correlated with the rate of pickup of liquor by the woolen materials passing through the bath so that the complete renewal of the bath liquor takes place in a period of l to 15 minutes: preferably the time for complete renewal is less than l0 minutes. lt has been found that these times are insufficient for a substantial loss of chlorine from the treating liquor to occur before coming into contact with the woolen material. Thus, the material as it passes through the bath takes up a controlled amount of virtually fresh liquor. There has been no opportunity under the conditions outlined for any extraneous substances present in the woolen materials, such as combing oils present in tops, to pass from the materials into the bath and to accumulate therein and interfere with the reaction. In consequence, it is possible to produce a much more closely standardized treated wool having a predictable degree of shrink resistance imparted thereto. Any adventitious salts present in the reagents employed as well as salts produced by reason of the adjustment of the pH value of the solution of the halogencontaining substance are likewise carried forward in the interstices of the materials and thus remain a substantially constant factor if, in fact, they have any effect upon shrink-resistance-imparting reactions at the concentrations in which they are present.

It has already been observed that the volume of liquid admitted to the bath is correlated with the rate of pickup of liquor by the materials passing therethrough. initially the bath is filled to the desired extent with liquor of the desired composition. The volume of liquor in the bath is then maintained substantially constant throughout substantially the whole of the run by metering fresh solution from each of the reservoirs into the bath in such proportions as to maintain the composition of the bath substantially constant. Only during the last few minutes of a run should the volume of liquor in the bath be allow to fall.

In an alternative form of the invention the woolen material is supplied with a controlled amount of treating liquor by substantially uniformly spraying liquor from a tank on to both sides of the material, The spraying may be done from a manifold located upon each side of goods passing upwards towards a nip. The tank receives liquor from the reservoirs referred to above and devices are provided to enable the contents of the tank to be replenished as the liquor is used. Accurate adjustment and uniform distribution of the pickup is secured by passing the sprayed material between the nip of a pair of rollers in the manner already indicated.

Considering in more detail the pH-adjusted sodium or potassium dichloroisocyanurate system as a typical one to which the invention is applicable, the aqueous solution of sodium or potassium dichloroisocyanurate is held in a reservoir at a pH value of substantially 5 to 6 at which it is stable. The second reservoir preferably contains a dilute solution of a mineral acid such as hydrochloric acid or of an acid salt such as sodium bisulfate or sodium dihydrogen phosphate or an organic acid such as acetic acid. One of the solutions also contains a wetting agent. These two solutions are admixed as required to produce a treating liquor having a pH value of 2.5 to 4.5, preferably about 3.5, which liquor is rapidly picked up by the wool before substantial decomposition can occur. After passing the nip the liquor in predetermined amount is held in contact with the wool for a period which is preferably sufficient for at least 95 percent of the dicliloroisocyanurate to exhaust upon the wool. Due to the short interval of time elapsing between reduction of pH value and pickup by the wool, the amount of decomposition occurring is negligible and is, in any event, a substantially constant factor throughout the run.

Similar considerations apply to an alkali metal hypohalite based system such as one using sodium hypochlorite and a mineral acid. In the case of the pH-adjusted sodium hypochlorite system to which the invention is applicable, an aqueous solution of sodium hypochlorite is held in a reservoir at a pH value of 8 to 10 at which it isstable and the second reservoir contains a dilute solution of a mineral acid such as hypochloric acid or of an acid salt such as sodium bisulfate or a suitable organic acid such as acetic acid. One of the solu tions, preferably the acid solution, contains a wetting agent. These two solutions are then mixed as required to produce a treatment liquor having a pH value of 3.0 to 5.0, preferably 3.0 to 4.0, which liquor is rapidly picked up by the wool before substantial decomposition can occur. After passing the nip a predetermined amount of liquor is present in the interstices of the material and is held in contact with the wool for a period which is preferably sufficient for at least percent of the active chlorine to exhaust upon the wool.

A third system 7 f64 the invention is applicable is one containing an alkali metal permanganate, e.g. potassium permanganate, an alkali metal or calcium hypochlorite and tttecs acid, such as acetic acid or hydrochloric acid, present in an amount sufiicient to reduce the pH of the liquor to below 5.

At the conclusion of the treatment any residual dichloroisocyanurate and reaction products derived therefrom are removed by washing the treated material with water and then with a dilute aqueous solution of a reducing agent or antichlor reagent which may be sodium sulfite. The thus treated material is the again washed with water and finally dried.

The following examples illustrate the nature of the inven tion:

EXAMPLE 1 Ten continuous lengths of wool tops, each weighing 20 gms. per meter are passed through a bath having a capacity of 4.5 liters filled with an aqueous solution containing 4.5 percent by weight of acetic acid, 1.0 percent of a nonionic wetting agent known as Tergitol TMN and 1.73 percent of sodium dichloroisocyanurate. This solution has a pH value of substantially 3.5. After passing through the solution the wool enters a precision nip adjusted so that the pickup of solution is 150 percent of the weight of the wool. The speed of the wool is 5 meters per minute; thus 1 kg. of wool passes through the bath and nip each minute, taking with it 5 liters of the above treating solution,

The bath is kept full by metering into it a liquor obtained by admixing (i) 750 cc. per minute ofa solution containing 9 per cent by weight of acetic acid and 2 percent of Tergitol TMN and (ii) 750 cc. per minute of 3.46 percent by weight of sodium dichloroisocyanurate having a pH value of 6.4. Such admixture takes place immediately prior to introduction to the treatment bath.

After passage through the nip the wool contains 2.6 percent of its own weight of sodium dichloroisocyanurate at pH 3.5. The wool is then allowed to fall upon a brattice moving at such a speed that the wool remains thereon for 1.5 to 2.0 minutes during which at least percent of the dichloroisocyanurate is exhausted. The wool then passes through the following baths: (i) a rinse bath of warm running water, (ii) aqueous 1 percent sodium sulphite solution, (iii) two successive rinses in water. The wool is then dried by continuous passage through a drying chamber.

SAmples of treated and untreated wool tops submitted to a standard washing test in the Dylan Cuber. Washing Machine gave the following figures: Untreated Control 32 percent; Treated material 4 percent shrinkage.

EXAMPLE 2 Ten continuous lengths of wool tops, each weighing 20 gms. per meter, are passed through a bath having a capacity of 4.5 liters and filled with a solution containing 53 cc. per liter sodium hypochlorite solution (15 percent available chlorine by weight), 18 cc. per litre of concentrated hydrochloric acid and 10 cc. per litre of Tergitol TMN (a nonionic wetting agent). This solution has a pH substantially 3. After passing through the solution the wool enters a precision nip so adjusted that the uptake of solution is percent of the weight of the wool. The speed of the wool is 5 meters per minute. Thus 1 kg. of wool passes through the bath and nip each minute, taking away with it 1.5 liters of the above treating solution.

The bath is kept full by metering into it a liquor obtained by admixing (i) 750 cc. per minute of a solution containing 106 cc. per liter of sodium hypochlorite solution (15 percent available chlorine by weight) and (i1) 750 cc. per minute of an aqueous solution containing 36 cc. per liter of concentrated hydrochloric acid (36 percent BC] by weight) and g. per liter of Tergitol TNM. These two solutions are stable for long periods and they are only admixed immediately prior to use.

Since the bath has a capacity of 4.5 liters and the mixture is used up at the rate of 1.5 liters per minute, the mixture remains in the bath for a period of 3 minutes. During this 3 minutes the loss of chlorine from the bath is negligible. The dwell time of the wool in the bath is 1.5 to 2.0 seconds.

After passing the precision nip the wool id allowed to fall upon the brattice moving at such a speed that the wool remains thereon for 1 minute and then passes through the following baths; (a) rinse bath of water, (b) aqueous 2 percent sodium sulfite solution at pH 8.5 and (c) two further rinse baths of water. The dwell time in these baths is seconds. The material is them dried.

Samples of treated and untreated wool tops were submitted to a standard washing test in the Dylan Cubex Machine with the following results: Untreated control 27 percent shrinkage; Treated material 5 percent shrinkage.

The invention is further illustrated in the accompanying drawing which is a flow sheet illustrating the use of an acidified solution of sodium dichloroisocyanurate. A constant head of aqueous sodium dichloroisocyanurate solution is maintained in a constant head tank C, whence it flows along an outlet line L in which is inserted a flowmeter F The flowmeter F controls the amount of sodium dichloroisocyanurate solution flowing along line L,. A constant head of mineral acid solution, e.g. hydrochloric acid solution, is maintained in constant head tank C whence it flows along an outlet line L in which is inserted a flowmeter F The flowmeter F controls the amount of acid solution flowing along line L The controlled quantities of sodium dichloroisocyanurate solution passing flowmeter F and of hydrochloric acid passing flowmeter F are delivered into a mixing tank M which is provided with a suitable stirrer to ensure adequate mixing. Tank M is provided with an overflow line L;,. When tank M is full to the overflow level the volume of liquid passing along line L is directly related to the sum of the volumes of liquid passing flowmeters F and F The overflowing liquid from tank M falls into a small reservoir R provided with an outlet line L. along which mixed liquid passes to the treating bath B which is located between a pair of rollers rotating in the directions shown. Bath B is provided with suitable liquid-tight ends. A continuous form of wool travelling from left to right passes over a roller and then vertically downwards into bath B and through an adjustable nip between the rollers generally designated N. This nip determines the pickup of liquid by the wool from bath B. After passing the nip the wool impregnated with a treating solution of acidified sodium dichloroisocyanurate passes round a further roller and then resumes its left to right travel on its way to a brattice or scray, not shown in the drawing, on which it remains for a time sufficient to ensure that the desired degree of oxidation of the wool takes place at a pH below 5.

Flowmeters F, and F are, in practice, set to deliver a total volume of liquid equal to the pickup at the nip N.

What is claimed is:

l. a process for imparting shrink resistance to wool and wool-containing materials which comprises (A) wetting-out a continuous form of such a material by immersing said material in a bath of aqueous liquor containing (a) a wetting agent, (b) a halogen-releasing shrink-resistance-imparting oxidizing agent for wool, and (c) a source of hydrogen ion other than a peracid present in an amount sufficient to reduce the pH value of the solution to below 5, the anion of said source of hydrogen ion being inert with respect to said halogen-releasing oxidizing agent, the residence time in said bath being suffrcient to insure thorough penetration and wetting of the wool but insufficient to allow any significant exhaustion of the liquor of the bath, (B) immediately after wetting-out, passing the wetted-out material through the nip between a pair of rollow so as to insure that the material is uniformly impregnated with a controlled amount of liquor in contact with said matenal until at least a desired amount of said halogen-releasing oxidizing agent has reacted with the wool with which it is in contact, the process being conducted while continuously metering quantities of aqueous solutions containing the halogen-releasing oxidizing agent, the source of hydrogen ion and the wetting agent into the aqueous liquor so as to maintain the composition thereof substantially constant, said metered quantities being correlated with the rate of pickup of liquor by woolen materials undergoing treatment so that the volume of said aqueous liquor remains substantially constant and complete renewal of said liquor takes place in l to 15 minutes.

2. A process according to claim H in which complete renewal of liquor takes place within 1 TO 10 minutes.

3. A process according to claim 1 in which the time of immersion of said materials in said bath is l to 2 seconds.

4. A process according to claim 1 in which the pickup of liquor at the nip between said rollers is to percent of the weight of the woolen material.

5. A process according to claim 1 in which the source of hydrogen ion is a mineral acid.

6. A process according to claim l in which the source of hydrogen ion is present in an amount sufficient to reduce the pH to between 2.5 and 4:5.

7. A process according to claim 1 in which the halogen releasing oxidizing agent for wool is sodium or potassium dichloroisocyanurate.

8. A process according to claim 1 in which the halogen releasing oxidizing agent is an alkali metal hypohalite.

9. A process according to claim 1 in which the thus treated wool is thereafter treated with a dilute aqueous solution of a reducing agent.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 2 ,9 Dated December 21, 1971 lnentor(s) Alan August Goldberg and John A. Fullwood It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 4 line 7, change "7 64" to to which Col. 4, line 9, change "tttecs" to an Signed and sealed this 17th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 80376-P69 a u,s. GOVERNMENT PRINTING OFFICE: I969 O366-334 

2. A process according to claim 1 in which complete renewal of liquor takes place within 1 TO 10 minutes.
 3. A process according to claim 1 in which the time of immersion of said materials in said bath is 1 to 2 seconds.
 4. A process according to claim 1 in which the pickup of liquor at the nip between said rollers is 100 to 150 percent of the weight of the woolen material.
 5. A process according to claim 1 in which the source of hydrogen ion is a mineral acid.
 6. A process according to claim 1 in which the source of hydrogen ion is present in an amount sufficient to reduce the pH to between 2.5 and 4.5.
 7. A process according to claim 1 in which the halogen releasing oxidizing agent for wool is sodium or potassium dichloroisocyanurate.
 8. A process according to claim 1 in which the halogen releasing oxidizing agent is an alkali metal hypohalite.
 9. A process according to claim 1 in which the thus treated wool is thereafter treated with a dilute aqueous solution of a reducing agent. 